Lewy body dementia
Definition & Facts
Lewy body dementia is thought to affect over one million people in the United States. It is often misdiagnosed as Parkinson's disease or Alzheimer's disease. As a result LBD is under-diagnosed in the United States. Lewy body dementia affects movement in a similar way to Parkinson's and thinking in a similar way to Alzheimer's. Therapies for Parkinson's and Alzheimer's may or may not work for those suffering from Lewy body dementia.
Lewy body dementia is named for scientist Dr. Friederich Lewy, who discovered the disease in the early 1900s. He found Lewy bodies in the brains of affected individuals. These bodies are abnormal clumps of alpha-synuclein proteins that collect in different parts of the brain.
Symptoms & Complaints
Visual hallucinations may also occur. People may see animals, objects or people that aren't there. Individuals with LBD may be seen talking with deceased relatives. Hallucinations of sound, touch and smell can also occur. In addition, some people may have trouble interpreting visual information. For example, depth perception, object-orientation, and directional sense may be impaired.
People with LBD experience disordered sleep. Rapid eye movement (REM) sleep behavior disorder is an early sign of LBD, coming years before a diagnosis of LBD. REM sleep disorder involves acting out dreams sometimes violently. Other sleep problems include excessive daytime sleep and trouble falling asleep or staying asleep.
Autonomic nervous system dysfunction may also afflict people with LBD. Changes occur in involuntary body processes. For instance, changes in heart rate and blood pressure can cause fainting or dizziness. Some people complain of excessive sweating or the opposite, lack of sweating and overheating. Digestive problems can cause severe constipation.
Psychiatric disturbances also occur. Depression and anxiety, aggression and delusions frequently accompany an LBD diagnosis. Psychiatric changes can be among the most distressing for families. Individuals with LBD may become convinced that family members or friends are impostors. They may also exhibit violent outbursts that are totally out of character for the individual.
Lewy bodies, the alpha-synuclein protein clumps, are thought to interfere with chemical regulation in the brain. The levels of two important chemicals are impaired. One of them, called acetylcholine, affects memory and learning. The other, called dopamine, affects movement, mood, and sleep.
Scientists aren’t sure what makes Lewy bodies start to build up in the brain. They’re also not sure why some people get LBD and others don’t. Researchers have not yet identified any specific causes of dementia with Lewy bodies. Most people diagnosed with LBD have no family history of the disorder, and no genes linked to LBD have been conclusively identified. Some health conditions worsen the odds of getting the condition. People with Parkinson’s disease or REM sleep behavior disorder have a higher risk of LBD.
Diagnosis & Tests
There is no single test to diagnose Lewy body dementia with the exception of brain analysis at autopsy. LBD can be difficult to diagnose, especially in the early stages. It can resemble other types of dementia and movement disorders and an individual's symptoms can vary greatly from day to day.
To be diagnosed with LBD, a person must show definite deficits in thinking and planning abilities. Poor memory may or may not be present. LBD is suspected if cognitive decline occurs along with changes in alertness, visual hallucinations, Parkinson's-like movement problems, serious sleep problems, and/or autonomic nervous system problems.
Testing is aimed to rule out other disorders and assess multiple areas of brain function. A comprehensive neurological examination will look at memory and thinking skills as well as reflexes, eye movements, and balance. Vital signs will be taken to check for changes in blood pressure and heart rate. Blood tests will be performed to look for vitamin deficiencies and endocrine disorders.
Treatment & Therapy
Acetylcholinesterase inhibitors help with alertness and thinking. These drugs are also commonly given to treat Alzheimer's disease. This class of drug works by increasing the levels of neurotransmitters believed to be important for memory, thought and judgment. They may also help with hallucinations. Side effects include digestive problems and frequent urination.
Parkinson's disease medications can help with movement problems in LBD. Medications such as carbidopa-levodopa treat symptoms such as rigid muscles and slow movement. Unfortunately, side effects of this medication can make some symptoms of LBD worse, such as confusion, hallucinations and delusions.
Antidepressant drugs are given to treat mood disturbances. The most commonly used antidepressants for LBD are selective serotonin reuptake inhibitors (SSRIs). Clonazepam or melatonin may be prescribed for REM sleep disorder.
Antipsychotic drugs are not used at all or are used with extreme caution until it is known how an individual with LBD will react. People with LBD can have severe, even life-threatening reactions to antipsychotic medications. Side effects include weight gain and Parkinson's-like symptoms that cannot be reversed.
Prevention & Prophylaxis
Most individuals diagnosed with LBD will need some sort of supportive care and help with activities of daily living. However, the progression of the disease varies greatly from one person to another. Most people can expect to live a decade or more with LBD. End-of-life planning should include appropriate palliative care. Arrangements should be made ahead of time if an autopsy is desired.